How to learn "signal integrity"?

1 Signal Integrity Basics

Putting it at the first point is enough to illustrate the importance of the basics of signal integrity. The so-called "high-rise building from the ground up" is the truth. To work on signal integrity, you must have a clear understanding of the theoretical basis of the entire signal integrity. At least read a few books on signal integrity to understand what signal integrity is; understand what the object and content of signal integrity research are; what factors are related to signal integrity; and where signal integrity affects the product One aspect; wait. The first book I remember is Eric's "Signal Integrity-Simplified", which is now known as the Blue Book "Signal Integrity Analysis", translated by Li Yushan and other authors, and then smashed the so-called ink book by Howard Johnson and Martin's "High-Speed ​​digital design-A handbook of Black Magic", the Chinese version is called "High-speed Digital Design", it is also relatively early, power integrity saw a "Integrated Circuit Power Integrity Analysis and Management" In the middle, the scalp is also smashed with an original English book "High-Speed ​​Digital System Design - A Handbook of Interconnect Theory and Design Practices". Of course, there are some big books and some original books in China, which are also very good, but nothing is complete.

The above two books are often recommended to the circuit design and hardware engineers around me. The signal integrity analysis is relatively simple and the entry is better. There is a second version, the title of the book has been changed, called "signal integrity and power supply." Integrity Analysis adds the previously missing S-parameters and power integrity, which is great. "High-speed digital design" is a bit more difficult, but it is considered a must-read book.

2 circuit principle

The circuit principle part should be a compulsory course for many engineers at the university. I remember that we learned at the time the analog and digital parts of Mr. Kang Huaguang's "Electronic Technology Foundation" and the "Circuit" by Qiu Guanyuan. Signal integrity is a part of the hardware design, but not only the design of the hardware circuit, but the circuit principle is an extremely important part of the signal integrity of high-speed circuits. Circuit principle design includes the design of the circuit system, block diagram and circuit, which is the basic skills that signal integrity engineers must have. This is also extended from the system design. How to achieve the goal of system design is the purpose of circuit principle design.

3 Familiar with each bus protocol

The logos in the above picture should appear more or less in our lives. So how much do you know about engineers who work with the interfaces or buses of these logos every day? In fact, as a signal integrity engineer, the bus protocol is something that every engineer must understand. Because this is the guide for our work, no matter how good you are, as long as it does not meet the requirements of the bus protocol, it is meaningless, because this is the basis for how the signal is transmitted, and also the basis for judging whether the signal meets the design requirements. Therefore, a signal integrity engineer who does not understand the agreement is not a good "chef."

4 Familiar with PCB layout design

At the current stage of rapid development of high-speed circuits, the design of principle schemes has become more and more simple. Today's consumer products, such as mobile phones, are just a few solutions. If the CPU is ok, then the solution and peripheral circuits are already determined, but the appearance and quality of the products designed by different companies are different, even the same company. The products designed are also different. The appearance is determined by ID and ME. The performance is different, which is different from PCB design. The PCB design of a product not only needs to connect the modules, but also needs to optimize performance, meet various compatibility tests, conform to production processes, and so on.

5 Familiar with PCB materials

PCB is the largest component in the product, so the raw materials for manufacturing this component become more and more important, especially for high-speed circuits. Whether the signal integrity meets the design requirements is partly determined by the PCB material. At present, there are thousands of PCB materials, and selecting materials that meet the product design is a work that more and more signal integrity engineers need to accomplish.

6 Familiar with evaluating various high speed interconnect devices

Signal integrity is a relatively broad concept, and the concept is mainly embodied in the design of the entire circuit and solution. High-speed interconnects in circuit links are an important part of signal integrity. Understand and be familiar with high-speed interconnect devices such as transmitter chips, receiver chips, connectors, cables, and more. Not only must consider its performance, but also cost, process parameter requirements, packaging, supplier quality, and more.

7 Familiar with at least one simulation software

One of the tasks of signal integrity is to improve the efficiency of product design, shorten the cycle of product development, and quickly bring products to market. Then, in the early stage of product design, it is necessary to simulate the key signals in the product, so that the R&D personnel can understand the risks of the products as much as possible and minimize the risks. Whether it is Hspice, Ansys designer/HFSS/SIwave/, or Hyperlynx or Sigrity, at least one simulation software should be familiar to signal integrity engineers. This will increase your confidence in design.

8 Familiar with test and measurement

For a product design, testing and measurement is an essential part of the product development phase. Signal integrity engineers must be proficient in using various test and measurement equipment. The basic equipment is real-time oscilloscope, sampling oscilloscope, network analyzer, impedance speedometer, signal source, voltage regulator, digital multimeter, etc. Analyzers, protocol analyzers, spectrum analyzers, probe stations, thermostats, and more. If you don't use the device, it's hard to find the problem of the product, so there is no way to design a good product. Of course, there are some basic ones, such as the use of soldering irons and hot air guns.

9 Ability to analyze and solve problems

Whether it's simulation or testing, analyzing and solving problems is the most important thing for a good signal integrity engineer. For many engineers today, it is very simple to get a test or simulation waveform. The complexity is to understand the meaning and representative problem of the waveform curve representation, and finally solve it. For example, if there is a non-monotonicity in the test, then first of all, we must know that this is a non-monotonic, and then analyze it because the test equipment is not calibrated, caused by human factors, or the choice of test points. Incorrect, or the problem of the chip itself, or the problem of impedance matching of the transmission line, etc., after finding the problem, the correct medicine can be prescribed.

I would like to offer to those children's shoes who are still outside the high-speed circuit, I hope to help you.